JP2802726B2 - Fluid type, especially hydraulic servo device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an input device which can be operated intentionally.
Force part; output part; input with limited elastic play
The amount of force or torque transmitted between the part and the output part
Allow relative motion between the input and output parts depending on
Drive coupling coupling the input part with the output part; input
Its set stroke due to relative movement between the part and the output part
Pre-given servo valve; working connection with servo valve
Coupled via connection and controlled by servo valve
Servo motor; and working between input and output
Work between the input and output sections to bring out the setting power
The present invention relates to a fluid type, particularly a hydraulic servo control device having a hydraulic preparation device .

[0002]

2. Description of the Related Art Servo controllers formed as power steering devices are widely used in tracked vehicles to facilitate driver steering operations.
In such a power steering device, the input part is typically formed or connected to a steering wheel, and the output part is assisted by a servomotor to turn the steered wheels of the vehicle.

[0003] Such a power steering device in a motor vehicle can be arbitrarily operated on the one hand by a driver, and on the other hand by an external control device in which the running vehicle follows a predetermined trajectory or performs an obstacle avoidance maneuver without the driver's operation. It is basically known to make it operable.

German Patent 3414891C
In the case of the hydraulic power steering system of the type mentioned at the beginning, which is known from the publication No. 2, the external control unit usually involves a hydraulic return flow from the servo valve to the hydraulic reservoir. Hydraulic pressure is generated by the return flow dam, which urges the end faces of the control slider of the servo valve in various manners through the control passage, thereby adjusting the displacement of the servo valve. In this way, the servo motor is operated to turn the wheels of the traveling vehicle by external control of the servo valve.

[0005] German Patent 3414891C
The structure known from the publication No. 2 presupposes a servo valve with a so-called open center, ie a servo valve which always flows at the center position while supplying a return flow by means of a hydraulic medium. Further, an external steering operation can be performed only at a position deviated from the center position of the servo valve when a return flow occurs even at this valve position. Typically, however, a servo valve, which normally flows through, shuts off the return flow at its end position, so that in some cases the full power of the hydraulic source can be introduced into the servomotor.

German Patent 3414891C
In the case of the structure according to the publication No. 2, a certain amount of return flow must be present even at the end position of the servo valve in order to enable external control. However, this means that the pressure source must also operate with very high power, even at the end position of the servo valve. The damping of the return flow is accompanied by a very large heating of the hydraulic medium, since an additional throttle acts in the damming state.

[0007] DE 26 52 815 C
It is known from JP-A 2 (1994) to combine an optionally controllable power steering device with an auxiliary hydromotor which is externally controllable and is always driven and coupled to the steering wheels of the traveling vehicle. The hydromotor can operate independently of the servomotor of the power steering device. Even ignoring the undesirably high construction costs here, the auxiliary hydromotor must always be moved together in the case of the usual voluntary control of the vehicle, and therefore quickly acts as an always active auxiliary steering resistance. Prevents easy steering operation.

[0008] German Patent 2818754A
It is known from the publication No. 1 that a traveling vehicle steering device is provided with an externally controllable servomotor acting on the steering wheel side of a steering wheel or a drop arm shaft. Again, in addition to the high construction costs, the auxiliary steering resistance caused by the servomotor has a disadvantageous effect, especially during rapid steering maneuvers. Furthermore, the return of the steering device is prevented by increased friction in the steering handle tube.

German Patent No. 3303063A
No. 1 and WO Patent No. 85/02380,
The servo valve is formed as a rotary valve device, the parts of which are directly connected to the input part and the output part of the split steering wheel shaft, and the input and output steering wheel shaft portions are elastically driven by a torsion rod with respect to each other. Combined
It relates to a hydraulic power steering device in which the relative rotation of these steering handle shaft portions is limited by a stopper integrated with the servo valve.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a servo control of the type mentioned at the outset, in particular at low construction costs, in which case, in particular, a closed-center servo valve can also be used. Is what you do.

[0011]

According to the invention, this object is achieved by the fact that, by means of an externally controllable adjusting device, the input and output parts of the drive valve which are connected to the servovalve can be displaced relative to each other.

According to the present invention, the external control is performed by establishing a servo valve.
It is based on the general idea that it involves directly in the drive train between the input part and the output part in order to cause a roke . In that case, in particular, there is the advantage that any type of basic servo valve, in particular a closed center servo valve, can be employed.

In an advantageous embodiment of the invention, the externally controllable adjusting device acts directly between the input part and the output part and enables a controlled relative movement between the input part and the output part. I have.

In this case, the adjusting device causes a relative displacement between the input part and the output part, ie the actuation of the servomotor, in the case of an external control operation, and the respective setting of the servomotor in the input part, in the case of normal optional control. in order to be able to sense the same as the force resistance, because the reaction force torque force to the corresponding reaction in the input portion is generated, the adjusting device has the advantage that bear a double function.

In an advantageous embodiment of the invention, the input section
Driving connection between minute and output part, between input part and output part
The elastic transmission element which causes elastic playParallel
The drive between the servo valve and the input or output part
An externally controllable adjusting device is arranged at the connection,
Depending on the device, the input or output part of the servo valve
Of the assigned servo valvePart controls the servo valve
Input or output partIs adjustable
Propose that. In this way, the adjustment device
During the displacement, the elastic stress of the elastic
It does not affect the operating resistance of the
Or it works with little power.

When the servo control device according to the present invention is formed as a power steering device for transmitting torque, it is advantageous to form the servo valve in the form of a rotary valve because the configuration is compact and simple.

[0017] Advantageous features of the invention are set out in the other claims. Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The motor vehicle power steering system shown in FIG. 1 has a two-part steering wheel shaft having an input part 1 and an output part 2 coaxial thereto. 1 is rigidly connected to a steering wheel (not shown) and an output part 2 has a pinion 3 formed thereon.
And cooperatively drive with the rack 4. The rack 4 operates steering wheels (not shown) of the traveling vehicle via a steering arm or the like connected thereto.

The input part 1 and the output part 2 are connected to one another in a torsional manner via a torsion bar 5 and possible relative rotation of the input part 1 and the output part 2 is controlled by stoppers (not shown) on opposite sides of a central position. Is limited in The torsion bar 5 is housed in axial holes in the input part 1 and the output part 2.

The end of the input part 1 on the output part 2 side is formed as a rotary valve 6. The rotary valve 6 surrounds the control bush 7 and is arranged in the output part 2 so as to be relatively non-rotatable.
And servo valves 6 and 7 are formed.

The control bush 7 is arranged inside the housing 8, in which case the various annular chambers are separated from each other by the packing between the control bush 7 and the housing 8. Via these annular chambers, the servo valves 6 and 7 are connected to the pressure pipe 9 and the return pipe 11 of the hydraulic servo pump 10 or another hydraulic pressure source in a basically known manner. The return pipe 11 leads to a hydraulic reservoir 12 to which the suction side of the servo pump 10 is connected. Servo valve 6,
7 is also connected to two working connection ports 13 and 14 communicating with respective chambers of the double-acting piston / cylinder device 15. This piston / cylinder device 15 is a rack 4
It is also drivingly connected to the output part 2 and thus acts as a servomotor of the steering device.

The relative rotation more or less relative to the torque transmitted between the input part 1 and the output part 2 may be one-way or other depending on the direction of the transmitted torque between the input part 1 and the output part 2. Occurs in the direction. This relative rotation of the torsion bar 5 to return causes the rotary valve 6 and the control bush 7 to be displaced relative to the central position in one direction or the other by a corresponding control distance. Thereby, during operation of the servo pump 10, a differential pressure directed in one direction or the other is applied to the working connection ports 13, 14 so that the servo motor formed by the piston and cylinder device 15 generates a corresponding set force. Occurs. By means of the setting force of the servomotor, the operating force required to operate the vehicle steering system at the steering wheel or input part 1 is significantly reduced.

An annular piston 16 is arranged between the input portion 1 and the housing 8 so as to be movable in the axial direction. The annular piston 16 forms two annular chambers 17 and 18 in the housing 8 separately. These annular chambers 17 and 18 are connected to the working connection ports 13 and 14 or both chambers of the piston / cylinder device 15 in a manner described later.

The annular piston 16 has an annular extension 19. This annular extension 19 has an inner helical tooth 20 and an outer helical tooth on the input part 1, and via an outer straight tooth 21 meshes with an inner straight tooth on the bush-like extension of the control bush 7. Therefore, the relative rotation between the input portion 1 and the control bush 7 or the output portion 2 is forcibly applied to the annular piston 1.
6 is moved in the axial direction.

The annular chambers 17, 18 are provided with operating connection ports 13, 14.
Or, while communicating with the chamber of the piston / cylinder device 15, the annular piston 16
Since an axial force similar to the set force acts, the annular piston 16 attempts to rotate the input part 1 and the control bush 7 or the output part 2 relatively back to their central position, whereby the input part 1 can be sensed as an operating resistance. A reaction force occurs. The magnitude of this reaction force is determined by the piston / cylinder device 15
It changes in the same way as the setting force of.

The features described above are basically known (WO
See Japanese Patent No. 85/02380).

[0027] Oite the present invention, the working connection ports 13, 14 to the piston-cylinder device an annular chamber 17, 18 15
A valve device having switching valves 22 and 23 which is connected to the first chamber or to an external pressure control device 24 is provided in particular .
This control device 24 has a control valve 25. Via this control valve 25, the annular chambers 17, 18 generate a differential pressure in one or the other direction acting between them (after switching the valves 22, 23 to a switching position not shown in FIG. 1). Controllably connected to the pressure side of pump 26 or to reservoir 12. The control valve 25 is externally (automatically) controlled, and more specifically, is controlled in connection with a traveling operation to be performed automatically, for example, an obstacle avoidance operation. In this way, an externally controllable axial force in one or the other direction acts on the annular piston 16, so that the input part 1 or the rotary sliding body and the output part 2 or the control bush 7
Are rotated relative to each other under the axial movement of the annular piston 16, and the piston-cylinder device 15
A set force corresponding to the axial movement of the vehicle 6 is generated, and the vehicle steering device can be operated accordingly. Or the steering wheel at this time, which is rigidly against rotation input portion 1 to the this is not constrained by a large force corresponding operating
It is I assume that is not manipulated in any way by hand
I am .

Unlike the embodiment shown in FIG. 1, the valve device having the switching valves 22, 23 is omitted, and the annular chamber 17,
18 to the control valve 25, i.e. the annular chamber 1
7, 18 and does not perform the connection with the work dynamic connection ports 13, 14 it is basically possible. When no external control action is taking place, the control valve 25 assumes the central position shown, in which no axial force acts on the annular piston 16. The steering device can therefore be operated manually in the usual manner. If an external control action is taken,
The control valve 25 is displaced in one direction or the other.

Instead of a separate pump 26, the servo pump 10 can optionally be connected to the pump connection of the control valve 25.

Even when an external control action is taking place, it is ensured that the differential pressure developed between the annular chambers 17, 18 and thus the axial adjustment force of the annular piston 16 is sufficiently limited. The driver can still operate the steering device. This set force produces a limited operating resistance which can be defeated by the driver when necessary for the input part 1.

The embodiment shown in FIG. 2 differs from the embodiment in FIG. 1 in that the annular chambers 17, 18 always have the working connection ports 13,1.
It differs in that it is connected to both chambers of the piston-cylinder arrangement 4.

The main difference is that the control bush 7 is rotatably connected to the output part 2. this
The control bush 7, which is axially supported inside the housing 8 by means of an annular flange 27 to enable rotational displacement, is positively connected to the output part 2 via a sliding bush 28. The sliding bush 28 has a helical tooth 29 at one end and a straight tooth 30 at the other end on the inner peripheral surface thereof. These helical teeth 29 and straight teeth 30 engage external teeth at adjacent ends of the control bush 7 and the output part 2, respectively. That is, when the sliding bush 28 moves in the axial direction, the control bush 7 rotates relative to the output portion 2.

The sliding bush 28 has an annular flange-shaped piston 31 on its outer periphery. By this piston 31, two annular chambers 3 are formed inside a part of the housing 8.
2, 33 are formed separately. These annular chambers 32,
Arranged inside 33 is an annular lap spring 34 which presses the piston 31 and thus the sliding bush 28 to a central position. Since the overlapping spring 34 is supported on the end face of the piston 31 with the axial rolling bearing 35 interposed therebetween, the piston 31 or the sliding bush 28 can be easily rotated even with a large pressing force of the annular overlapping spring 34.

The annular chambers 3 are closed off from one another and from the other internal chambers of the housing 8 by a packing 36.
2, 33 are connected to the control valve 25 of the external pressure control device 24 via connection ports 37, 38. In the illustrated central position of the control valve 25, the same pressure is applied to the annular chambers 32, 33, so that the lap spring 34 always holds the piston 31 and the sliding bush 28 in the central position. Accordingly, the control bush 7 and the rotary valve 6 of the servo valves 6 and 7 are relatively displaced from the center position only when a torque is acting between the input portion 1 and the output portion 2. In this way, the usual optional operation of the power steering device can be performed.

On the other hand, when a pressure difference is created between the annular chambers 32, 33, the sliding bush 28 moves more or less axially to the left or to the right, whereby the output part 2 is moved to the input part 1 The control bush 7 is rotated with respect to the output part 2 and therefore also with respect to the input part 1 while it is moved at all or only slightly with respect to. In this way, for the external steering action, the servo valves 6, 7 can be adjusted externally, so that the piston and cylinder device 15 can be operated externally.

As an alternative to the embodiment shown in FIG. 2, the input part 1
When a reaction force similar to the set force is prevented from acting, the annular piston 16 and the annular chambers 17 and 18 can be omitted.

It is conceivable to connect the input section 1 to a steering handle (not shown) or other operating means via a control mechanism. The control mechanism reacts as soon as a large force or torque is transmitted between the steering wheel or the steering means and the input part 1 and returns the control valve 25 at least partially to the illustrated central position. In this way, it is ensured that the driver can operate the steering device in the reverse of the "desired" adjustment direction by the steering operation even in the case of an automatic steering operation.

In the embodiment shown in FIG. 2, the servo pump 10 can also serve the purpose of the pump 26 in some cases, so that the latter pump 26 can be omitted.

In all embodiments, if the control device 24 is to be operated at a pressure level independent of the servo pump 10, it is advantageous to provide an auxiliary pump 26.

[0040]

According to the present invention, it is possible to obtain a servo control device which can use a servo valve of a closed center, particularly at a low cost of construction.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of a hydraulic servo device according to the present invention.

FIG. 2 is a sectional view of a second embodiment of the hydraulic servo device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input part 2 Output part 5 Torsion rod 6 Rotary valve 7 Control bush 15 Servo motor 16 Annular piston 17 Annular chamber 18 Annular chamber 31 Piston 32 Annular chamber 33 Annular chamber

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-50277 (JP, A) JP-A-61-500542 (JP, A) JP-A-60-105271 (JP, U) JP-T2 2- 2749 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B62D 6/02 B62D 5/083

Claims (8)

(57) [Claims] An input part (1) which can be arbitrarily operated, and an output part.
Input part with force part (2) and limited elastic play
(1) and the output part (2) are connected and both parts (1, 2)
According to the magnitude of the force or torque transmitted to both parts
Elastic transmission element (5) allowing relative movement between (1, 2)
And its setting strike due to the relative movement between the two parts (1, 2)
Servo valves (6, 7) with pre-set rooke
And a drive valve coupled to the output part (2)
(6, 7) and working connection ports (13, 14).
Servo mode controlled by servo valves (6, 7)
(15), between the input part (1) and the output part (2)
To pull out the setting force acting between the two parts (1, 2)
Fluid type with an adjusting device (16, 17, 18)
In the hydraulic servo controller, a service for controlling the adjusting devices (16, 17, 18) is provided.
Control valve that can be controlled externally independently of the boval valves (6, 7)
A servo control device provided with (25). 2. The method according to claim 1, wherein the externally controllable adjusting device acts directly between the input part and the output part to enable a controlled relative movement between the input part and the output part. Item 2. The servo control device according to Item 1. 3. The control device according to claim 2, wherein the externally controllable adjusting device is capable of sensing the input portion as an operating resistance during normal operation and applying a reaction force that changes in the same manner as the set force of the servomotor. Servo control device. 4. In parallel with a resilient transmission element for drivingly connecting an input part and an output part to create an elastic play between the input part and the output part, between the servo valve and the input part or the output part. An externally controllable adjusting device is arranged in the drive coupling of the motor, by means of which the portion of the servo valve assigned to the input or output portion is adjusted for the input or output portion to control the servo valve. The servo control device according to any one of claims 1 to 3, wherein the servo control device can be used. 5. A reaction force device is arranged in series with an adjusting device between a portion corresponding to an input portion or an output portion of a servo valve, and the reaction force device can sense an operation resistance at an input portion and can control a servo motor. 5. The servo control device according to claim 4, wherein a reaction force that changes similarly to the set force can be given. 6. The servo valve according to claim 1, wherein the servo valve is formed as a rotary sliding device.
The servo control device according to any one of the above. 7. The adjusting device has an annular piston which is coaxial with respect to the axis of the servovalve, which is formed as a rotary sliding device, which can be moved axially by means of fluid pressure and which can be engaged by various gears. Characterized in that the input part and the output part, or the part of the servo valve assigned to the input part or the output part, cooperate such that these parts rotate relative to each other during the axial movement of the piston. The servo control device according to claim 6. 8. A control mechanism is arranged between the input part and its operating mechanism, the control mechanism reacting to a force or torque transmitted between the input part and the control mechanism, and a threshold value of the force or torque. The servo control device according to any one of claims 1 to 7, wherein control is performed so that the adjustment device is invalidated or the set force is reduced as described above.